True, but the fact that one has a 3-phase supply doesn't mean that one has to have a 3-phase DB. I have a 3-phase supply, but there's not a 3-phase DB to be found anywhere!
Kind Regards, John
Triple phase electric supply in a house
- Thread starter ssmyther
- Start date
Kind Regards, John
The house is a standard domestic unit so chances are that running it on a single phase should be well within the scope of the DNO supply. The cut-out fuses may be either 80 or 100amp (may be marked on cut-out), if so then running the house on single is perfectly feasible.
Also having 3-phase split across the house systems does increase risk for the householder. There is always the potential for 400/415 being available between appliances.
Having a 3-phase supply to my domestic property I feel qualified to comment as I found lighting was on one phase and sockets on another. ie differing phases and hence 400/415 within the same rooms.
Have had the 3-phase dist-board replaced by a single phase consumer unit, but have retained 3-phase to my workshop machinery.
As to meter standing charge, my 3-phase meter standing charge is identical to neighbours' single phase standing charge (Scottish Power).
Also having 3-phase split across the house systems does increase risk for the householder. There is always the potential for 400/415 being available between appliances.
Having a 3-phase supply to my domestic property I feel qualified to comment as I found lighting was on one phase and sockets on another. ie differing phases and hence 400/415 within the same rooms.
Have had the 3-phase dist-board replaced by a single phase consumer unit, but have retained 3-phase to my workshop machinery.
As to meter standing charge, my 3-phase meter standing charge is identical to neighbours' single phase standing charge (Scottish Power).
You keep saying that.
Can you explain what circumstances would need to arise for the householder to be exposed to 400V?
Who knows what stupid things the great British public can get up to
Some idiot mucking about trying to combine a lighting circuit and a power circuit which are on different phases.
Or even a well meaning sparkie who thinks it might be a good idea to split lighting circuits across different phases to provide mains failure diversity.
All maybe remote, but all a possibility
Before I got mine converted to all the same phase I found kitchen sockets on different phases. Separate ends of the kitchen maybe, but a good example of how things can get screwed up.
Some idiot mucking about trying to combine a lighting circuit and a power circuit which are on different phases.
Or even a well meaning sparkie who thinks it might be a good idea to split lighting circuits across different phases to provide mains failure diversity.
All maybe remote, but all a possibility
Before I got mine converted to all the same phase I found kitchen sockets on different phases. Separate ends of the kitchen maybe, but a good example of how things can get screwed up.
An extraordinarily unlikely scenario and, in any event, if the same idiot tried the same thing when the circuits were on the same phase, there could be all sorts of dangerous consequences.
What is your problem with that - that is could result in 400V PDs between different switches in multiple switch plates? In fact, having switches on the same plate on different circuits is a potential hazard (with regard to safe isolation) even if the circuits are on the same phase.
Quite. Incredibly remote, I would say. I wouldn't actually put any money on anyone ever having come to harm as a result of the sort of scenarios you are postulating.
Again, the chances of anyone coming to harm as a result of that would seem vanishingly small. In order for anyone to experience a 400VD PD, you would probably need four separate faults - L-E faults on two appliances and failure of the fault protection on both of the circuits concerned.
There is obviously a theoretically greater risk when 400V PDs (rather than 230V ones) exist within an installation, but I really don't think that, in practice, it is a significant risk. 'Idiots' or 'well-meaning people doing silly things' will always exists, and are quite cable of introducing hazards even with just one phase to play with.
Kind Regards, John
I ain't carrying a cross on this one - just giving a personal opinion so let's call it quits
The OP is free to do as he wishes
The OP is free to do as he wishes
Yes, but twice you gave a personal opinion which was very alarmist, not one based on any sensible analysis of the facts, and which might have made the OP worry unnecessarily about the safety of his house wiring.
Fair enough. You are obviously free to have (and cannot be criticised for having) an ultra-cautious personal opinion. However, as BAS has said, I think it reasonable that we should attempt to put the facts in some perspective for the OP, who will then hopefully be in a position to decide what he wants to do.
Kind Regards, John
It's a four bed bungalow with central heating what do you estimate the load to be ? 10A per phase ! At tea time
Sure, in the OP's case, it doesn't make a blind bit of difference which way it's done. However, my observation still remains - that if a 3-phase supply supply is going to be retained, then if one is going to make comments about whether the load should be spread across all three phases or put just on one, the former would (at the time I wrote the above) have been more what I would have expected! ... However, since the comment was from Jackrae, and given his subsequent comments, I imagine that he was probably suggesting that one should avoid the potential 400V/415V pds, so, given those views, his comment is perhaps now more understandable than it seemed when I posted my comment!It's a four bed bungalow with central heating what do you estimate the load to be ? 10A per phase ! At tea time
Kind Regards, John
I think Jackrae is correct, there is more potential danger for a DIYer who doesn't know what he is doing on a property that has three separate phases.
Yes, and I would agree with that, too. Perhaps I misunderstood, because I thought the discussion was about the pros and cons of having ('living with') a 3-phase supply, rather than the (undoubtedly true) greater opportunities for a DIYer to get into trouble if 'playing' with it.
Kind Regards, John
The scenario of a switch plate fed by two circuits which may well be on two seperate phases would be a worry if a DIYer was meddling. Or decorating a room, and loosening socket and switch plates, fed by two phases.
Admittedly, this kind of thing could happen anywhere, but it's fairly rare for domestic houses to have three phase. Usually guest houses and farm houses, I suppose.
Admittedly, this kind of thing could happen anywhere, but it's fairly rare for domestic houses to have three phase. Usually guest houses and farm houses, I suppose.
I've already agreed with that. However, I've been trying to relate my comments to this thread. No-one has said anything about DIYing. The OP said that he was buying a house which had a 3-phase supply, asked about the pros and cons of keeping it as such and asked whether a normal 'domestic' electrician would be OK working on a 3-phase installation. No mention of any DIY intent.
In passing, I would say that, because of the isolation risks, it would be very bad practice to have two switches on the same plate fed from different circuits in a single-phase installation, let alone different phases - and that's true in relation to both decorating and 'DIY meddling'.
Kind Regards, John
I would say over 99% of houses have a switch plate fed from two circuits (single phase). There was a time when a note was placed inside the switch box, saying something about the accessory being fed from more than one circuit, and to isolate disconnect more than one fuse or circuit breaker.
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